The present invention generally, relates to visual display arrangements for a simulator to develop improved realism and, more particularly, to wide angle display devices of the type in which the screen of a Cathode Ray Tube (CRT) is reflected into a concave mirror by a beam splitter, through which an observer sees the image of the CRT screen in the mirror.
Such devices are sometimes known as WAC heads (wide angle collimated heads) and commonly have the beam splitter inclined upwardly and away from the lower edge of the mirror, i.e., towards the observer, and the CRT is commonly mounted with its tube axis vertical and with its screen facing down, over the beam splitter.
These devices are used to display out-of-the-window screens in the cockpit of a flight simulator. Situations arise in such simulators today in which a substantially wider field-of-view is desired than a single device can provide, which typically is about 45.degree.. If two wide angle display devices are mounted side by side, it has been impossible to avoid an obvious gap between them in the composite display, as a result of eye movement from the ideal viewing position.
An object of the present invention is to provide arrangements which overcome or compensate for such gaps and which allow the images of two CRT screens to be substantially continuous. If the images overlap, there may be a data overlap, which must be taken into account in generating the respective video signals for the two CRTs. The present invention is not concerned with this aspect of use of the arrangement which would involve correctly adjusting the geometry of the two video signals in the area of overlap of the two displays.
In describing the invention, the expression "device axis" is the axis containing the radius through the center of the mirror. Also, the expressions "device azimuth" and "device elevation" are used to mean angles from the device axis measured, respectively, as the .theta. and .phi. coordinates of conventional spherical polar coordinates referenced to a z-axis parallel to the CRT axis. The lateral edges of the mirror are at the maximum values of the device azimuth.